Next fall I’m teaching a course in basic web development. HTML, intro to CSS, that sort of thing. A student emailed me and said there was a prerequisite that he’d never heard, and asked me what it was. I didn’t know either, since there shouldn’t have been any. The school switched course management tools this year, and there are a few bugs, so I wrote to the guy in charge of that and asked him what the prerequisite was for my class.